1. Field of the Disclosure
This disclosure relates generally to drill bits that include sensors for providing measurements relating to downhole parameters, methods of making such drill bits and drilling systems for using such drill bits.
2. Brief Description of the Related Art
Oil wells (wellbores) are usually drilled with a drill string that includes a tubular member having a drilling assembly (also referred to as the bottomhole assembly or “BHA”) with a drill bit attached to the bottom end thereof. The drill bit is rotated to disintegrate the earth formations to drill the wellbore. The BHA includes devices and sensors for providing information about a variety of parameters relating to the drilling operations (drilling parameters), behavior of the BHA (BHA parameters) and formation surrounding the wellbore being drilled (formation parameters). To drill the wellbore, fluid pumps are turned on to supply drilling fluid or mud to the drill string, which fluid passes through a passage in the drill bit to the bottom of the wellbore and circulates to the surface via the annulus between the drill string and the wellbore wall. When the mud pump is on, the pressure inside the drill bit is greater than the pressure on the outside of the drill bit, thereby creating a pressure differential across the drill bit body. This pressure differential causes the drill bit body to act as a pressure vessel, affecting the measurements made by the weight-on-bit sensors in the drill bit. Therefore, there is a need for an improved drill bit and a method that corrects for the change in the weight and torque measurements caused by the differential pressure in the drill bit.